In the consumer electronics and computer industries, transmission of audio signals from a host player to remote device speakers has generally been accomplished over an analog, wired interface comprising speaker wires. With the advent of digital audio content, the desire to maintain the pristine digital audio signal as far as possible along the audio signal chain has motivated designers to pursue digital interfaces to replace signal-loss-prone analog speaker wires.
The High-Definition Multimedia Interface (HDMI) is an all-digital audio/video interface capable of transmitting uncompressed streams. HDMI provides an interface between any compatible digital audio/video source, such as a set-top box, a DVD player, a PC, a video game console, or an audio video (AV) receiver and a compatible digital audio and/or video monitor, such as a digital television (DTV).
FIG. 1 shows an example of a prior art audio/video multi-channel system 100 that includes a source 105, e.g., an HDMI AV receiver with a centralized amplifier, connected via an HDMI cable to HDMI DVD player 110 and also connected via an HDMI cable to a display 115, e.g., an HDMI television. The HDMI AV receiver 105 is also connected via analog speaker wires to a set of six speakers 120, each connected point-to-point from the HDMI AV receiver. Speakers 120 can be positioned to encircle a listener and create a realistic, three-dimensional audio experience.
Although wired digital interfaces offer high quality and fidelity, the ease of setup and mobility is lacking due to the constraints of the physical connections. Wireless links, such as WiMedia® ultra-wideband (UWB), are capable of transporting data for high quality, real-time streams, but data is only one element of a multi-channel, audio transmission. Timing information is essential for proper reproduction of the real-time data stream. Accurate control of the timing of the output of the speakers not only affects coordination of audio with a video stream, but also has an impact on distance and movement effects of the sound. For example, a slight delay in the audio output can create the effect of a greater distance between the listener and the origin of the sound.
Clock transportation and reproduction is typically not addressed by wireless links. Wired links transmit a clock signal to the various modules, but transmitting a clock signal wirelessly is typically limited in accuracy.